STEVE INSKEEP, HOST:
We have surprising news this morning that rats save lives. They're doing that in Cambodia, where it turns out that rats can help to locate long buried landmines. Now that I know this, I never have to worry about landmines in my neighborhood again. Michael Sullivan reports from Cambodia.
MICHAEL SULLIVAN, BYLINE: Most rats you want to catch, and then - well, never mind. But these rats, these rats you want to let out of the cage. This morning, that's about 5 a.m. And they get to work quickly, their noses close to the wet grass as they search for explosives buried below. The on-site supervisor, Hulsok Heng, charts their progress on a clipboard.
HULSOK HENG: They are very good. You see one - 200 square meter - they clear about only 30 minutes or 35 minutes. If you compare to deminer, maybe two day or three day.
SULLIVAN: That's right. The guy with a metal-detecting machine will take a lot longer. And that's because...
HENG: The deminer, they will pick up all the fragmentation, all metal in the ground. But the rat, they pick up only the smell of TNT. They not pick up the fragmentation or metal or nail or piece of crap in the ground.
SULLIVAN: The rat is not going to be fooled by a battle cap, a nail, none of that.
HENG: Yeah, none of that.
SULLIVAN: Only explosives like TNT. These aren't kitchen rats. They're African pouched rats. And they're monsters, about 2 pounds each and 2 feet long from head to tail. They don't see very well, but their sense of smell is fantastic. And a Belgian NGO, Apopo, has taken that idea and run with it, dispatching rats from its training center in Tanzania to post-conflict countries - first in Africa, Mozambique, Angola and now Cambodia, where decades of conflict ended only recently and left the country littered with unexploded ordinance - according to the government's estimates, millions of mines, bombs or shells.
HENG: (Foreign language spoken).
UNIDENTIFIED MAN #1: (Foreign language spoken).
SULLIVAN: Hulsok Heng says the rats have a leg up on mine-sniffing dogs, too, because dogs bond with humans - rats, not so much.
HENG: If it's a dog, they recognize the handler. If the handler's sick, that dog cannot work with other people. With the rat, anybody can work with - they cannot recognize the handler. So anybody can use the rat.
SULLIVAN: And a rat won't set off a mine if it steps on one accidentally - not heavy enough - a mine-sniffing dog, problem. One of the rat wranglers here, Sean Na, has worked with both and says there's another advantage to rats.
SEAN NA: (Foreign language spoken, laughter).
SULLIVAN: Na says the rats don't bite as hard. I walk with Hulsok Heng to a 200-square meter area roped off with measuring tape to have a look at one of the rats at work.
OK, who do we have here?
UNIDENTIFIED MAN #2: (Foreign language spoken).
SULLIVAN: So here's the test now - right now - for Victoria. About 1 meter from where we're standing, you have planted a mine. Let's see if she finds it.
SULLIVAN: Victoria ambles down the line she's tethered to, nose to the ground, then stops and pushes her nose high up in the air, sniffing repeatedly until she locks on. Then, she takes one more step and scratches the ground.
SULLIVAN: So that click we just heard was the sign for the rat to come and get the banana...
SULLIVAN: Because she scratched the ground when she found...
HENG: Yeah. After the rat pick up and they're scratching, we click. And then we give food reward, like banana.
SULLIVAN: No TNT, no banana. And to make sure the rats get it, the handlers plant dummies. Next to Victoria's patch, there's another rat working named Pit.
HENG: So they finish two mine already. So that the black number seven, this is the dummy. Dummy, that mean the smell from battery, car filter, oil filter, tuna fish can, that we make to confuse the rat.
SULLIVAN: You're trying to trick him.
HENG: Yeah because if they scratch on other smell, we don't give food.
SULLIVAN: Pit walks the line and doesn't go for the fake. A few meters down the line, though, there's another mine. And this one's no dummy. It's packed with explosives. Pit stops, sniffs and quickly scratches the damp earth.
SULLIVAN: Hulsok Heng just smiles.
HENG: He never found the dummy. He smell only TNT.
SULLIVAN: He's never fallen for a dummy?
HENG: No, never.
SULLIVAN: And the other rats?
HENG: Sometimes, yeah. Sometimes they scratch for a dummy, but we don't give them food. Then the rat, they learn. But some rats, they are more clever than the other.
SULLIVAN: And what happens to a rat who's not clever and is lazy too? Do you just give them to the cat?
HENG: No (laughter) we keep training and training.
SULLIVAN: That training, according to the Apopo website, costs about $6,500 all in. But the rats have a long lifespan, about 8 years, and low maintenance.
HENG: Because they eat only banana - one banana or two banana a day. That's it. And they never get sick.
SULLIVAN: We go back to the office for a look at the rats' spacious, air-conditioned cages. First impression, these rats live better than a lot of people in Cambodia. The boss here, Theap Bunthourn, doesn't disagree.
THEAP BUNTHOURN: We want to protect our investment. We want to keep them good, healthy all the time so that they can perform in a field more efficiently.
SULLIVAN: There are still some skeptics out there who just won't trust a rat. Apopo field supervisor Hulsok Heng, who's got 20 years' experience looking for and blowing up mines and other ordinance, isn't one of them. In fact, he says, there are some things the rats can do that metal machines can't.
HENG: One type of mine from Chinese, we call 72 Alpha - the metal very, very small. But for the rat, they smell the TNT very good. So they can pick up that mine.
SULLIVAN: So you would actually trust a rat's nose over a metal detector in that instance.
HENG: Yeah, but if you have both, it's very good.
SULLIVAN: In other words, the giant African rats are just another tool in the demining box - not meant to replace dogs or machines but to augment them, to make it quicker and easier to deal with the legacy of the country's brutal past, a legacy that still kills or maims dozens every year. Coordinator Theap Bunthourn says he hopes his rats in training will be deployed for real come September. For NPR News, I'm Michael Sullivan outside Siem Reap, Cambodia.
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